This application claims a priority based on Japanese Patent Application No. 2000-78549 filed Mar. 21, 2001, the entire contents of which are incorporated herein by reference for all purposes.
1. Field of the Invention
The present invention relates to a technique of deciding weather of an image of a virtual world displayed on a screen of a display unit.
2. Related Art Statement
Recently, entertainment apparatuses such as a television game machine, which can perform flight simulation, drive simulation, etc. utilizing 3D graphics animation, become popular.
In this kind of entertainment apparatus, an operator uses an operating unit connected to that apparatus to operate an operatable object such as an airplane or car, to move the object everywhere in a virtual world. That entertainment apparatus generates a dynamic image obtained by taking a picture of the operatable object moving in this virtual world by a virtual camera, and displays the dynamic image on a screen of a display unit connected to that apparatus.
In the conventional entertainment apparatus that can perform flight simulation, drive simulation, etc., weather phenomena such as cloud, rain and wind are reflected on an image displayed on a screen or on operability of an operatable object, to increase the entertainingness.
However, in this kind of conventional entertainment apparatus, predetermined weather phenomena are assigned to each area of the virtual world in advance. And, weather phenomena assigned to an area to which an image displayed on a screen of a display unit belongs or an area where the operatable object is located are reflected on that image or the operability of that operatable object. Or, the predetermined weather phenomena are reflected at random on an image displayed on a screen of the display unit or the operability of the operatable object, so as to change weather phenomena as time passes.
Accordingly, in the former case, weather phenomena are fixed for each area, and an operator can not enjoy such weather change experienced in the real world. On the other hand, in the later case, weather phenomena reflected on an image displayed on a screen of the display unit or on the operability of the operatable object are changed at random, and the operator can not forecast weather coming next, which he/she can bring out depending upon his/her experiences.
Thus, those techniques can not give reality to a flight simulation and a drive simulation.
Thus, an object of the present invention is to increase the entertainingness by giving more reality to weather phenomena reflected on an image displayed on a screen of a display unit or operability of an operatable object.
To attain the mentioned object, in the present invention, weather in each global area obtained by dividing a map, expressing the whole virtual world into a plurality of global areas is decided at predetermined intervals in accordance with a behavior model that sets a condition for the global area in question, and considering area information given in advance to the global area in question. The mentioned condition is decided from a cyclically-changing event. Further, weather in each local area obtained by dividing each global area into a plurality of local areas is decided at predetermined intervals, in accordance with the weather of the global area in question decided as above, and considering area information given in advance to the local area in question.
Here, the condition set for each global area by the behavior model and decided from a cyclically-changing event is, for example, quantity of sunshine per a unit time at each date and time in each global area, which is decided from one year fluctuation of quantity of sunshine owing to the revolution of the earth and one day fluctuation of quantity of sunshine owing to the rotation of the earth.
Further, the area information given in advance to each global area is, for example, general information indicating that the global area in question is land or sea. On the other, the area information given in advance to each local area includes detailed information such as the height of the local area in question, in addition to the general information indicating that the local area is land or sea.
According to the present invention, weather of an arbitrary local area that belongs to an arbitrary global area is decided based on weather given to the global area in question and area information given in advance to the local area in question. Accordingly, it is possible to decide weather of an arbitrary local area considering the area information of that local area, while correlating the weather to local areas in the neighborhood of the local area in question.
Further, according to the present invention, weather of an arbitrary global area is decided based on the condition decided from the cyclically-changing event (for example, quantity of sunshine per a unit time at present day and time in the global area in question) and the area information given in advance to the global area in question. Accordingly, it is possible to cyclically change weather in each local area as in the real world.
By this, it is possible to give more reality to weather phenomenon that is reflected on an image displayed on a screen of a display unit or on operability of an operatable object, in an entertainment apparatus that can execute a flight simulation game, a drive simulation game, and the like.
Or, when the present invention may be applied to the case in which an image obtained by photographing an arbitrary area in a virtual world using a virtual camera is only displayed on a screen of a display unit. In that case, more reality can be given to a weather phenomenon reflected on an image taken by said camera, thus realizing an unprecedented entertainment apparatus.
According to the present invention, for example, a means for deciding weather in each global area at predetermined intervals comprises:
a first means for deciding a temperature, pressure and water vapor content in each global area at predetermined time intervals, based on the quantity of sunshine per a unit time at a time concerned, the area information given in advance to said global area, and last-decided temperatures, pressures, and water vapor contents of the global area in question and global areas adjacent to said global area, with said quantity of sunshine being set for the global area in question by said behavior model; and
a second means for generating a model expressing a global weather phenomenon located in each global area, as a global weather model, at predetermined time intervals, and based on the temperature, pressure and water vapor content in each global area, decided by said first means.
Further, a means for deciding weather in each local area at predetermined intervals comprises:
a third means for deciding a temperature, pressure and water vapor content in each local area at predetermined intervals, based on the temperature, pressure and water vapor content of a global area to which the local area in question belongs, the area information given in advance to said local area, and last-decided temperatures, pressures and water vapor contents of the local area in question and local areas adjacent to said local area; and
a fourth means for generating a model expressing a local weather phenomenon located in each local area, as a local weather model, at predetermined time intervals, and based on the temperature, pressure and water vapor content in each local area, decided by said third means, the area information given in advance to said local area, and the global weather model located in said local area by said second means.
Here, the global weather phenomenon means a weather phenomenon, such as a high/low pressure area, an air current, or the like, that affects weather of the whole virtual world. Further, the local weather phenomenon means a weather phenomenon, such as cloud, rain, wind, or the like, that affects local weather,
According to the above-described arrangement, the first through fourth means can be designed separately from and independently of one another (modularization), and burdens on the designing can be dispersed.